It might help if you mention the context in which you saw the term being used, otherwise I can only assume dec is short for a decatherm = one million British thermal units
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"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
Assuming DEC means decatherm.
A therm is 100,000 BTU's (look at your home gas bill, it is usually in therms)
Deca is times 10
Decatherm is 1,000,000 BTU's
At a typical heating value of 1000 BTU's per cubic foot of natural gas, 1 Decatherm = 1,000 Cubic Feet or 1 MCF
We believe is more like a slang term used mostly in Alberta and Saskatchewan, Canada. They were talking about Gas Volume, they were trying to size a compressor package. The person that came to the engineers with 12 Decs of gas to size a compressor package thought it was a common measurement unit so he didn't ask what a Dec was, but we've never heard of it.
Seems like a lot, since a Dec of cards is pretty small. But, then, a Dec can be a very long period of time, when you're a kid waiting for the 25th...
Sorry, BigInch, my nightscope is on the fritz ever since it took a couple of armor piercing rounds thru it...but my dowsing rods still work as good as ever!
Seems to me that it's a clear problem of TLA application.
For example, during a meeting, you don't understand a term, you keep quiet thinking that everyone else does. In fact nobody does, but they are not going to fess up either.
TLA = three letter abbreviation. The bane of the petrochem industry.
I know this is a late reply, but I just stumbled across this. A dec of natural gas means 1000 standard m³/day of natural gas. There's about 28.32 decs for a MMSCFD. The e symbol is how it is represented, but I think its meant to be E (like how calculators sometimes show 10). So the symbol e3 is actually E3 which means 1000. Sometimes you'll see a dec displayed more intuitively as 10³m³/day too.
[I just noticed the dates on this thread, I don't know how I missed it back in March]
A lot of those crazy Canucks use the E3M3 terminology directly. I've heard "DEC" a few times, and always got that it was a thousand m^3. When I ask what gas composition is used to convert E3M3 (a volume) to "DEC" (an energy) I'm generally asked to mind my own business because no one knows.
It is like the Australians using "Joule" for a volume like it means something. I teach a class on this stuff and generally start with a question for the class "what units do you use for flow volume?" and the range of answers is amazing. Then I follow up with, since you can't agree I'll use MCF (if they ever do agree I'm screwed because my slides are in MCF).
Oh well, if the OP didn't get a better answer then he built a tiny little compressor for 12 MCF/d when he needed a BIG compressor station for 340 MMCF/d. Hopefully he got clarification in the contract when he said he could build $20 million worth of compression for $45k.
I love the business guys that want a compressor or pipeline sized for xx MMBTU/day. Even the contracts spell out fees based on BTU's. A compressor or pipeline doesn't have a clue what a BYU is. When you ask for a gas analysis, its, What??? That is more information than I'm allowed to give out. So you just assume .6 gravity 1000 BTU/cf. Then you hear the business guy say that the other company came up with a compressor 10% smaller. Meanwhile you bribe the bussiness dudes admin person and find out that the gas is 1175 BTU/cf. duh!!!!